1. Field of the Invention
The present invention relates to an insertion device including an insertion section extended along a longitudinal axis, and an assist tool detachably attached to the insertion section and actuated to cause a propulsion force for movement along the longitudinal axis to act on the insertion section.
2. Description of the Related Art
Japanese Patent No. 5326049 discloses an endoscope device (insertion device) including an insertion section extended along a longitudinal axis, and an assist tool (spiral unit) attached to the insertion section to be rotatable around the longitudinal axis. In the endoscope device, a motor (driving source) attached to a held section (operation section) of an endoscope is driven, thereby transmitting a driving force generated by the motor to the assist tool attached to the insertion section via a shaft or the like extended inside the insertion section. The transmission of the driving force causes the assist tool to rotate relative to the insertion section around the longitudinal axis. A fin spirally extended around the longitudinal axis is provided on an outer peripheral surface of the assist tool. As the assist tool rotates around the longitudinal axis with the fin pressed by a lumen wall or the like, a propulsion force acts on the insertion section and the assist tool toward one side in a direction along the longitudinal axis. In other words, the propulsion force to move the insertion section along the longitudinal axis acts on the insertion section.